Portable lighting systems incorporating deformable light sheets

ABSTRACT

In accordance with certain embodiments, illumination systems include a flexible light sheet that may be wound within and unwound from, or folded within and unfolded from, a storage unit having a power source for powering light-emitting elements on the light sheet.

RELATED APPLICATION

This application claims the benefit of and priority to U.S. ProvisionalPatent Application No. 61/834,183, filed Jun. 12, 2013, the entiredisclosure of which is hereby incorporated herein by reference.

FIELD OF THE INVENTION

In various embodiments, the present invention generally relates toelectronic devices, and more specifically to array-based electronicdevices.

BACKGROUND

Portable lights that incorporate conventional illumination sourcestypically represent a compromise between portability and functionality.Incandescent and halogen lamps are fragile, generate significant amountsof heat, and consume a relatively large volume. Furthermore, theygenerally function as point sources that emit light at high intensityfrom a small volume, whereas in many applications it is desirable todistribute a significantly lower intensity over a relatively large areato provide more even illumination and reduce glare. Such goals may beachieved (at least in part) via the use of optics and diffusers, butthese typically increase the volume, reduce the efficiency, and increasethe cost—all undesirable traits for portable lighting.

Solid-state illumination sources such as light-emitting diodes (LEDs)are not as fragile as conventional illumination sources, but LEDs posechallenges in terms of heat dissipation and light distribution. LEDsthemselves are relatively small but typically are driven at a relativelyhigh current to achieve high light intensity per LED. This high drivecurrent leads to two disadvantages. First, the heat from the LED must bemanaged. This is typically accomplished with a thermal-managementsystem, either passive or active, which may include use of a metal-cladprinted circuit board (MCPCB), heat sinks, fans, or the like. These tendto be relatively large and expensive, decreasing the portability andadoption of such portable lighting sources. The second disadvantage isthat the light is still emitted with high intensity from a small volume,resulting in undesirably limited light-distribution patterns and highglare. As mentioned above, these may be addressed but typically at theexpense of portability and cost.

Common to all of these illumination sources are constraints based ontheir physical size and structure. They are relatively rigid, or formedon rigid circuit boards, which limits, for example, the ability to varythe two-dimensional conformation of a luminaire (or other lightingsystem) based on them. While various semi-flexible systems have beenmanufactured using a large number of relatively small rigid circuitboards attached to a flexible backing, these only have flexibility inone direction and have a relatively high risk of damage if they areflexed or bent in the opposite direction. The large number of electricalconnections between the circuit boards, which are flexed and stressedduring operation, also leads to potential reliability issues. Finally,such approaches are relatively costly because of the large number ofseparate circuit boards and connections that are required.

In view of the foregoing, a need exists for systems and techniquesenabling the low-cost design and manufacture of compact reliableportable lighting systems having broad light distributions, low glarewith the ability to produce different light-distribution patterns, andthe ability to create conformationally variable (e.g., foldable,rollable, and/or bendable) illumination systems.

SUMMARY

In accordance with certain embodiments of the present invention,lighting systems incorporate light sheets that may be deployed in anopen conformation for illumination of at least a portion of theirsurroundings and, when not in use, compressed, rolled, folded, orotherwise placed into a more compact conformation for portability.Lighting systems in accordance with embodiments of the invention mayincorporate a storage unit for storage of the light sheet betweendeployments thereof, and the storage unit may incorporate thereon ortherein a power source for supplying power to the light sheet. The lightsheet may be flexible and preferably contains thereon an array oflight-emitting elements interconnected with thin conductive traces.

In an aspect, embodiments of the invention feature an illuminationdevice that includes or consists essentially of a flexible light sheet,a storage unit, a winding mechanism, and a power source. The flexiblelight sheet includes or consists essentially of (i) a flexiblesubstrate, (ii) a plurality of light-emitting elements disposed over thesubstrate, and (iii) a plurality of conductive traces disposed on thesubstrate and electrically interconnecting the plurality oflight-emitting elements. The storage unit is configured to accept andcontain the light sheet in a rolled configuration therewithin. The lightsheet is wound around an axis (e.g., a central axis) of the storage unitwhen contained therewithin. The storage unit is also configured todispense at least a portion (i.e., some or all) of the light sheettherefrom via unwinding of the light sheet from the rolledconfiguration. The winding mechanism is utilized for winding and/orunwinding the light sheet around the axis of the storage unit. The powersource is disposed within and/or on the storage unit and is utilized tosupply power to at least an unrolled portion of the light sheet andthereby illuminating the light-emitting elements of at least theunrolled portion.

Embodiments of the invention may incorporate one or more of thefollowing in any of a variety of combinations. The light sheet may be atleast partially wound around an outer surface of the storage unit. Thewinding mechanism may include or consist essentially of a hand crankand/or a spring. The winding mechanism may be motorized. When the lightsheet is extended from the storage unit, the thickness of the lightsheet may be 5 mm or less. The light sheet may include an array ofoptical elements (e.g., lenses) disposed over the light-emittingelements. The array of optical elements may include or consistessentially of separate and discrete optical elements each associatedwith one or more light-emitting elements, or the array of opticalelements may include or consist essentially of a unified layer or slabof material defining optical elements each disposed over, or otherwiseassociated with, one or more light-emitting elements. A water-resistantor waterproof coating may be disposed over the light-emitting elementsof the light sheet. The coating may substantially conform to thenon-planar topography of the light-emitting elements (and, e.g., otherelements such as conductive traces) thereunder. The top surface of thecoating may be planar notwithstanding the non-planar topography of thelight-emitting elements (and, e.g., other elements such as conductivetraces) thereunder. The power source may include or consist essentiallyof a battery disposed within the storage unit (e.g., at or proximate theaxis around which the light sheet is wound), a solar cell and/orcapacitor (e.g., a super-capacitor) disposed on an outer surface of thestorage unit, and/or a connector configured for connection to anexternal source of power (e.g., an AC outlet). The light sheet may beconfigured to be wound within the storage unit to a radius of curvatureof 50 mm or less.

The light-emitting elements may include or consist essentially ofbare-die light-emitting diodes (and/or bare-die lasers) and/or packagedlight-emitting diodes (and/or packaged lasers). The light-emittingelements may emit substantially white light, which may have a correlatedcolor temperature is in the range of 2000 K to 10,000 K. A stiffener maybe disposed along at least a portion (i.e., part or all or substantiallyall) of a leading edge of the light sheet (i.e., the edge of the lightsheet emerging first out of the storage unit during unwinding and/or theedge of the light sheet disposed farthest away from the storage unitwhen the light sheet is fully unwound). A rotary electrical joint may bedisposed within the storage unit, and the rotary electrical joint may beconfigured to preserve electrical contact between the light sheet andthe power source during winding and unwinding of the light sheet. Thepower source may include or consist essentially of a battery (e.g., aflexible battery), a capacitor (e.g., a flexible capacitor), or a solarcell (e.g., a flexible solar cell) disposed on a surface of the lightsheet opposite the light-emitting elements. The illumination device mayalso include, disposed within the storage unit, (i) drive circuitryconfigured to convert power from the power source for use by thelight-emitting elements, (ii) control circuitry configured to control atleast one emission characteristic of the light-emitting elements, and/or(iii) communication circuitry configured to transmit information to orfrom the illumination device.

When the light sheet is fully extended from the storage unit, a trailingedge of the light sheet may remain mechanically anchored within or onthe storage unit. In some cases, only the unrolled portion of the lightsheet is illuminated, and a rolled portion of the light sheet disposedwithin the storage unit is unilluminated. The illumination device mayhave an ingress protection rating of at least IP 65, as specified byInternational Protection Marking in International ElectrotechnicalCommission (IEC) standard 60529. The light sheet may include thereon oneor more fasteners for positioning of the light sheet when the lightsheet is at least partially extended. The one or more fasteners mayinclude or consist essentially of a hook, a hook-and-loop fastener, ahole, a clamp, a grommeted hole (i.e., a hole with a grommet disposedpartially or entirely therearound), and/or a magnet. The storage unitmay include thereon one or more fasteners for positioning of the lightsheet when the light sheet is at least partially extended. The one ormore fasteners may include or consist essentially of a hook, ahook-and-loop fastener, a hole, a clamp, a grommeted hole, and/or amagnet. The plurality of light-emitting elements disposed over thesubstrate may form a fixed pattern in the shape of one or more symbolsand/or letters.

In another aspect, embodiments of the invention feature an illuminationdevice that includes or consists essentially of a flexible light sheet,a storage unit, one or more sensors, and a power source. The flexiblelight sheet includes or consists essentially of (i) a flexiblesubstrate, (ii) a plurality of light-emitting elements disposed over thesubstrate, and (iii) a plurality of conductive traces disposed on thesubstrate and electrically interconnecting the plurality oflight-emitting elements. The flexible light sheet includes at least onecrease in a first direction for folding therealong. The light sheet mayalso include one or more creases in directions other than the firstdirection for folding therealong. The storage unit is configured to (i)accept and contain the light sheet in a folded configurationtherewithin, and (ii) dispense at least a portion of (i.e., some or allof) the light sheet therefrom via unfolding of the light sheet from thefolded configuration. The one or more sensors are each associated with acrease (and some or all creases may have multiple sensors associatedtherewith), and are configured to detect if the light sheet is folded orunfolded along the associated crease. The power source is disposedwithin and/or on the storage unit and responsive to the one or moresensors. The power source supplies power to an unfolded portion of thelight sheet and thereby illuminates only the light-emitting elements ofthe unfolded portion, light-emitting elements on a folded portion of thelight sheet remaining unilluminated.

Embodiments of the invention may incorporate one or more of thefollowing in any of a variety of combinations. When the light sheet isextended from the storage unit, a thickness of the light sheet may be 5mm or less. The light sheet may include an array of optical elements(e.g., lenses) disposed over the light-emitting elements. The array ofoptical elements may include or consist essentially of separate anddiscrete optical elements each associated with one or morelight-emitting elements, or the array of optical elements may include orconsist essentially of a unified layer or slab of material definingoptical elements each disposed over, or otherwise associated with, oneor more light-emitting elements. A water-resistant or waterproof coatingmay be disposed over the light-emitting elements of the light sheet. Thecoating may substantially conform to a non-planar topography of thelight-emitting elements thereunder, or the top surface of the coatingmay be planar notwithstanding a non-planar topography of thelight-emitting elements thereunder. The power source may include orconsist essentially of a battery disposed within the storage unit (e.g.,at or proximate the axis around which the light sheet is wound), a solarcell and/or capacitor (e.g., a super-capacitor) disposed on an outersurface of the storage unit, and/or a connector configured forconnection to an external source of power (e.g., an AC outlet). Thelight-emitting elements may include or consist essentially of bare-dielight-emitting diodes (and/or bare-die lasers) and/or packagedlight-emitting diodes (and/or packaged lasers). The light-emittingelements may emit substantially white light, which may have a correlatedcolor temperature in the range of 2000 K to 10,000 K.

A stiffener may be disposed along at least a portion of a leading edgeof the light sheet. The power source may include or consist essentiallyof a battery (e.g., a flexible battery), a capacitor (e.g., a flexiblecapacitor), or a solar cell (e.g., a flexible solar cell) disposed on asurface of the light sheet opposite the light-emitting elements. Theillumination device may also include, disposed within the storage unit,(i) drive circuitry configured to convert power from the power sourcefor use by the light-emitting elements, (ii) control circuitryconfigured to control at least one emission characteristic of thelight-emitting elements, and/or (iii) communication circuitry configuredto transmit information to or from the illumination device. When thelight sheet is fully extended from the storage unit, a trailing edge ofthe light sheet may remain mechanically anchored within or on thestorage unit. The illumination device may have an ingress protectionrating of at least IP 65, as specified by International ProtectionMarking in International Electrotechnical Commission (IEC) standard60529. The light sheet may include thereon one or more fasteners forpositioning of the light sheet when the light sheet is at leastpartially extended. The one or more fasteners may include or consistessentially of a hook, a hook-and-loop fastener, a hole, a clamp, agrommeted hole (i.e., a hole with a grommet disposed partially orentirely therearound), and/or a magnet. The storage unit may includethereon one or more fasteners for positioning of the light sheet whenthe light sheet is at least partially extended. The one or morefasteners may include or consist essentially of a hook, a hook-and-loopfastener, a hole, a clamp, a grommeted hole, and/or a magnet. Theplurality of light-emitting elements disposed over the substrate mayform a fixed pattern in the shape of one or more symbols and/or letters.

These and other objects, along with advantages and features of theinvention, will become more apparent through reference to the followingdescription, the accompanying drawings, and the claims. Furthermore, itis to be understood that the features of the various embodimentsdescribed herein are not mutually exclusive and can exist in variouscombinations and permutations. Reference throughout this specificationto “one example,” “an example,” “one embodiment,” or “an embodiment”means that a particular feature, structure, or characteristic describedin connection with the example is included in at least one example ofthe present technology. Thus, the occurrences of the phrases “in oneexample,” “in an example,” “one embodiment,” or “an embodiment” invarious places throughout this specification are not necessarily allreferring to the same example. Furthermore, the particular features,structures, routines, steps, or characteristics may be combined in anysuitable manner in one or more examples of the technology. As usedherein, the terms “about,” “approximately,” and “substantially”mean±10%, and in some embodiments, ±5%. The term “consists essentiallyof” means excluding other materials that contribute to function, unlessotherwise defined herein. Nonetheless, such other materials may bepresent, collectively or individually, in trace amounts.

Herein, two components such as light-emitting elements and/or opticalelements being “aligned” or “associated” with each other may refer tosuch components being mechanically and/or optically aligned. By“mechanically aligned” is meant coaxial or situated along a parallelaxis. By “optically aligned” is meant that at least some light (or otherelectromagnetic signal) emitted by or passing through one componentpasses through and/or is emitted by the other.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings, like reference characters generally refer to the sameparts throughout the different views. Also, the drawings are notnecessarily to scale, emphasis instead generally being placed uponillustrating the principles of the invention. In the followingdescription, various embodiments of the present invention are describedwith reference to the following drawings, in which:

FIGS. 1A and 1B are an isometric view (FIG. 1A) and a cross-sectionalview (FIG. 1B) of an illumination system with a wound light sheet, inaccordance with various embodiments of the invention;

FIGS. 2A-2C are schematic illustrations of an illumination system with afoldable light sheet, in accordance with various embodiments of theinvention;

FIG. 3 is a schematic illustration of an illumination system with afoldable light sheet, in accordance with various embodiments of theinvention;

FIG. 4 is an isometric view of an illumination system featuring a lightsheet integrated on an electronic device in accordance with variousembodiments of the invention;

FIGS. 5A and 5B are side views of an illumination system having a standto facilitate directional illumination in accordance with variousembodiments of the invention;

FIG. 6 is an isometric view of an illumination system featuring a lightsheet incorporated within a case in accordance with various embodimentsof the invention;

FIG. 7 is an isometric view of an illumination system featuring a lightsheet connected to a power source within a holder in accordance withvarious embodiments of the invention;

FIGS. 8A and 8B depict an illumination system featuring a light sheetconforming to an object such as a camping stove, in accordance withvarious embodiments of the invention;

FIGS. 8C and 8D depict illumination systems in which light sheets pop up(FIG. 8C) or are unrolled (FIG. 8D) from a storage unit in accordancewith various embodiments of the invention;

FIG. 9A is a circuit diagram of a portion of a light sheet in accordancewith various embodiments of the invention;

FIGS. 9B and 9C are schematic plan views of light sheets in accordancewith various embodiments of the invention;

FIG. 10A is a schematic plan view of an extended light sheet inaccordance with various embodiments of the invention;

FIGS. 10B and 10C are schematic cross-sectional views of portions ofcoated light sheets in accordance with various embodiments of theinvention;

FIG. 10D is a schematic cross-sectional view of a wound light sheet inaccordance with various embodiments of the invention;

FIGS. 10E-10H are schematic cross-sectional views of illuminationsystems in accordance with various embodiments of the invention;

FIGS. 11A and 11B are schematic cross-sectional views of portions ofillumination systems incorporating vias for electrical interconnectionin accordance with various embodiments of the invention;

FIGS. 12A-12C are schematic views of illumination systems incorporatingshaped light sheets or shaped arrangements of light-emitting elements inaccordance with various embodiments of the invention; and

FIG. 13 is a schematic cross-sectional view of a portion of anillumination system incorporating optical elements in accordance withvarious embodiments of the invention.

DETAILED DESCRIPTION

Various embodiments of the present invention feature a thin light sheetthat does not require any additional heat sinking or thermal management.In some embodiments, the light sheet may also be flexible and may becurved or folded to achieve one or more specific characteristics orattributes, for example, to permit manufacture of a compact, foldablesystem and/or to achieve a specific light-distribution pattern.

FIGS. 1A and 1B depict exemplary lighting devices in accordance withembodiments of the present invention, although alternative devices orsystems with similar functionality are also within the scope of theinvention. As depicted, the lighting devices include or consistessentially of one or more flexible light sheets 110, which include aflexible substrate 165 on which is formed an array of light-emittingelements (LEEs) 140. In some embodiments of the present invention, lightsheet 110 includes or consists essentially of an array of LEEs 140electrically coupled by conductive elements formed on a flexiblesubstrate, for example as described in U.S. patent application Ser. No.13/799,807, filed Mar. 13, 2013 (the '807 application), or U.S. patentapplication Ser. No. 13/970,027, filed Aug. 19, 2013 (the '027application), the entire disclosure of each of which is incorporated byreference herein. In some embodiments of the present invention, lightsheet 110 is relatively thin, for example having a total thickness inthe range of about 0.5 mm to about 3 mm. In some embodiments of thepresent invention, light sheet 110 does not require any additionalthermal management or heat sinking.

FIGS. 1A-1B show an isometric view and a cross-sectional view of alighting device 100 in accordance with various embodiments of thepresent invention. Lighting device 100 includes flexible light sheet 110that may be rolled up into a drum 170. In some embodiments, flexiblelight sheet 110 may be rolled up into and unrolled out of the drum 170using a winding handle 177, as shown, while in other embodiments lightsheet 110 may be rolled and unrolled by other means, for example bymanually wrapping light sheet 110 around drum 170, or by means of amotor that wraps light sheet 110 into or around drum 170, or by means ofa spring-loaded mechanism, similar to that of a window shade. Duringstorage, light sheet 110 is rolled into drum 170, while during operationall or a portion of light sheet 110 may be unrolled or extended fromdrum 170.

The large number of relatively small LEEs 140 that are distributed overthe substrate 165 provides uniformly distributed light emission from arelatively large surface with relatively low glare.

FIGS. 1A and 1B depict an edge stiffener 175 along all or substantiallyall of the leading edge of light sheet 110; however, this is not alimitation of the present invention, and in other embodiments an edgestiffener 175 may be formed along one or more portions of the leadingedge of light sheet 110, while other embodiments may not include anyedge stiffener 175. In some embodiments, edge stiffener 175 may includeone or more hooks, holes, snaps or the like (not shown in FIGS. 1A and1B) that may be used as an attachment point to the leading edge of lightsheet 110, for example to support lighting device 100 when unrolled andextended. In some embodiments, light sheet 110 may include one or morehooks, holes, snaps, or the like (not shown in FIGS. 1A and 1B) that maybe used as an attachment point to one or more portions of light sheet110, for example to support lighting device 100 when unrolled andextended. In some embodiments, drum 170 may include one or more hooks,holes, snaps or the like (not shown in FIGS. 1A and 1B) that may be usedas an attachment point to drum 170, for example to support lightingdevice 100 when unrolled and extended.

FIG. 1B shows a battery 180 positioned within drum 170 and insiderolled-up light sheet 110. One or more optional drive boards 187,containing a drive circuit to power or partially power light sheet 110,or control boards, containing a control circuit to control variouscharacteristics of light sheet 110, or communication boards to providecommunication to and/or from lighting device 100, may also be positionedwithin drum 170. In some embodiments of the present invention, drive,communication, and/or control circuitry may be formed on light sheet 110rather than on boards separate and discrete from lights sheet 110. Insome embodiments of the present invention, battery 180 is anon-rechargeable battery, while in other embodiment battery 180 isrechargeable. In some embodiments of the present invention, battery 180may be charged by connection to a primary power source, for example theAC mains system, while in other embodiments battery 180 may be chargedby other means, for example by a solar cell, by an internal generator(for example a wind-up generator), by energy harvesting (for example byshaking or moving lighting system 100), by connection to an externalcharging source, or the like. In some embodiments, light sheet 110 mayhave one or more solar cells, formed on the side opposite LEEs 140,which may be used to charge battery 180. In some embodiments of thepresent invention, all or a portion of drum 170 may be covered with oneor more solar cells that may be used to charge battery 180.

In some embodiments of the invention, drum 170 contains a rotaryelectrical joint that maintains electrical contact between light sheet110 (and the LEEs 140 thereon) and a power source such as battery 180and/or other control or communication elements while enabling freerotation of portions of the light sheet 110 as it is wound in or on drum170 and unwound from drum 170. For example, the rotary electrical jointmay feature a stationary conductive component that contacts the insideor outside of a rotating conductive component (e.g., a conductive ring)that rotates as light sheet 110 is wound or unwound. Suitable rotaryjoint configurations are well-known in the art.

In some embodiments of the present invention, light sheet 110 may beenergized or de-energized using a switch located on drum 170 or on lightsheet 110. In some embodiments of the present invention, the lightintensity from light sheet 110 may be variable, for example LEEs 140 maybe dimmable, to permit modification of the light level emitted bylighting device 100. In various embodiments, only a portion of the lightsheet 110 is unrolled from drum 170 and only that unrolled portion isilluminated in order to, e.g., prevent excessive heat build-up and/orpower consumption that might result from illuminating the LEEs 140 ofthe rolled portion of light sheet 110 remaining within drum 170. Forexample, movement of the rotary joint mentioned above may be utilized tomeasure (or “meter”) the amount of light sheet 110 exiting the drum 170during unrolling, and then only those LEEs 140 (e.g., exposed rows,strings, or groups of LEEs 140, which may be individually addressable)are illuminated. Such embodiments enable the selection of a particularillumination level and/or area based on the current needs of the user,who may adjust the amount of illumination simply by rolling andunrolling light sheet 110 into and out of drum 170. In embodiments ofthe invention featuring foldable lighting devices (as described below),portions of the light sheet 110 that are unfolded from a storage unit orother container may be selectively illuminated in a similar fashion. Forexample, mechanical, magnetic, or piezoelectric sensors may be utilizedat the folding joints in the light sheet 110 to signal when a particularportion or panel of light sheet 110 is deployed (e.g., unfolded), andthen only the LEEs 140 on such portion(s) may be illuminated.

In some embodiments of the present invention, lighting device 100 may bewater-resistant or waterproof. In some embodiments of the presentinvention, lighting system 100 may be dust-resistant or dirt-resistant.In some embodiments, lighting device 100 may be configured to protectlight sheet 110, for example to provide mechanical protection,protection from dust, water, etc. One method for rating different levelsof environmental protection is an IP rating as specified byInternational Protection Marking in International ElectrotechnicalCommission (IEC) standard 60529, providing classification of degrees ofprotection provided by enclosures for electrical equipment, the entiretyof which is hereby incorporated by reference herein. In someembodiments, lighting device 100 may have any IP rating, for examplefrom IP00 to IP 69k, or any other IP rating. In some embodiments of thepresent invention, lighting device 100 has an IP 65 rating or an IP 66rating or an IP 67 rating or an IP 68 rating. In some embodiments, drum170 may be constructed from metal or plastic, for example aluminum,steel, acrylic, polystyrene, polyester, or the like. In someembodiments, light sheet 100 may be conformally coated or encapsulatedwith a transparent or partially transparent material to create awater-resistant or waterproof coating on light sheet 110. In someembodiments, the transparent material has a transmittance to awavelength of light emitted by LEEs 140 of at least 75%, at least 85%,or at least 95%.

In some embodiments of the present invention, light sheet 110 may havedimensions in the range of about 75 mm to about 300 mm wide and in therange of about 15 cm to about 1000 cm long; however, the dimensions oflight sheet 110 are not a limitation of the present invention, and inother embodiments light sheet 110 may have different dimensions. In someembodiments, light sheet 110 has a width of about 15 cm and a length ofabout 2 m. In some embodiments, light sheet 110 has a width of about 30cm and a length of about 1 m. Light sheet 110 is shown as having arectangular shape in FIGS. 1A and 1B; however, this is not a limitationof the present invention, and in other embodiments light sheet 110 mayhave any shape, for example a trapezoid, a triangle, a circle or thelike. In some embodiments, drum 170 may have a diameter in the range ofabout 25 mm to about 300 mm; however, the diameter of drum 170 is not alimitation of the present invention, and in other embodiments drum 170may have a different diameter.

FIGS. 2A-2C show a lighting device 200, which is a variation on lightingdevice 100 shown in FIGS. 1A-1B. LEEs 140 are not shown in FIGS. 2A-2Cfor simplicity. While lighting device 100 incorporates a roll-up lightsheet 110, lighting device 200 incorporates folding light sheet panels210. FIG. 2B shows four light sheet panels 210 making up lighting device200; however, this is not a limitation of the present invention, and inother embodiments lighting device 200 may incorporate fewer or morelight sheet panels 210. In some embodiments of the present invention,the panels 210 are substantially rigid, while in other embodimentspanels 210 are flexible.

FIG. 2B shows one embodiment of the present invention in which thelighting device 200 is suspended from a hook, nail or other wall-mountedfeature. In some embodiments, a mounting fixture, for example a holewithin light sheet 110 or an optional edge stiffener 175 (FIG. 1A, butnot shown in FIGS. 2A-2C) may be used to attach lighting device 200 tothe wall-mounted feature. FIG. 2C shows one embodiment of the presentinvention, in which lighting device 200 rests on a surface and forms adesk lamp. In this embodiment, the light-emitting surfaces of panels 210are facing outwards; however, this is not a limitation of the presentinvention, and in other embodiments the light-emitting surfaces ofpanels 210 may face inwards.

As discussed herein, in some embodiments of the present invention abattery or other power source may be incorporated in drum 170. Whiledrum 170 is shown as a cylinder in FIGS. 1A and 1B, this is not alimitation of the present invention, and in other embodiments drum 170may have other shapes. For example, drum 150 may have a cross-sectionalsquare shape (as shown in FIGS. 2A and 2C), a cross-sectional triangularshape, a cross-sectional hexagonal shape, or any other shape.

In some embodiments, other elements may be incorporated into lightingdevices of the present invention. For example, in some embodiments alighting device may incorporate a two-way radio, a receiving radio, aflashlight, a first aid kit, and/or a storage compartment, for examplefor money, matches, lighter, rope, minor or the like, a knife, or otheritems.

FIG. 3 shows another embodiment of the present invention, identified aslighting device 300. In this embodiment, instead of being rolled, aswith lighting device 100, lighting device 300 is folded like aconcertina or accordion. LEEs 140 are not shown in FIG. 3 forsimplicity. In lighting device 300, light sheet 110 is coupled to ahousing 310. In some embodiments of the present invention, the housing310 may include one or more batteries 180 and/or one or more drive,communication, or control boards 187 or other features, as discussedherein. In some embodiments of the present invention, one or more solarcells or energy harvesting devices may be incorporated in or on housing310 or on substrate 165.

In some embodiments of the present invention, the relatively thin natureof the light sheet, as well the ability to operate with no additionalthermal management, may permit the incorporation of lighting devicesinto equipment or structures inaccessible to conventional solid-statelighting because of size and/or heat limitations.

FIG. 4 shows one embodiment of the present invention in which a lightsheet-based lighting device is integrated into a mobile phone or otherelectronic device. FIG. 4 shows an electronic device 410, light sheet110, and LEEs 140. It is often desirable for mobile phones, as well asother electronic devices such as tablets, phablets, laptop computers,remote controls, radios, etc., to have a thin form factor. In someembodiments of the present invention, the light sheet may have athickness in the range of about 0.5 mm to about 2 mm and may beincorporated by mating the light sheet to a portion of electronic device410, for example the case of a cell phone or tablet, or it may beincorporated by building it into the structure of the device itself. Insome embodiments of the present invention, light sheet 110 may be matedto a portion of electronic device 410 by lamination, glue, adhesive, orthe like. In some embodiments of the present invention, conductivetraces as formed on substrate 165 (for example, as described in the '807and '027 applications) may be formed on a portion of electronic device410, eliminating the need for substrate 165. In some embodiments of thepresent invention, light sheet 110 may be controlled in part byelectronic device 410. For example, in some embodiments of the presentinvention, light sheet 110 may flash or blink or change intensity uponreceiving an incoming call or text or email. In some embodiments, theindication may be different to signal different events. In someembodiments of the present invention, light sheet 110 may be turned onor off by electronic device 410. In some embodiments of the presentinvention, the intensity of light emitted by light sheet 110 may becontrolled by electronic device 410.

In some embodiments of the present invention, electronic device 410 mayincorporate a stand, for example a stand 510, as shown in FIGS. 5A and5B, to permit positioning of electronic device and light sheet 110 toprovide illumination in one or more directions. For example, FIG. 5Ashows illumination in a down direction, while FIG. 5B shows relativelylateral illumination. However, the illumination directions shown inFIGS. 5A and 5B are not limitations of the present invention, and inother embodiments the illumination direction may be upwards or in anydirection.

FIG. 6 shows an embodiment of the present invention in which light sheet110 is incorporated into a case 610, for example an equipment case.Light sheet 110 may be relatively thin and be relatively easilyincorporated into the lid, sides and/or bottom of case 610, permittinguniform, low-glare illumination of the interior of case 610 withoutconsuming a large amount of space within case 610 and without generatinga significant amount of heat within case 610.

FIG. 7 shows another embodiment of the present invention, in whichbattery 180 or an alternate power source is contained within a holder710 and is attached to light sheet 110 through a connecting cord 730 andan optional connector 720. In some embodiments of the present invention,optional connector 720 may permit separation of connecting cord 730 fromholder 710. In some embodiments of the present invention, connector 720is a waterproof connector. In some embodiments of the present invention,light sheet 110 incorporates an attachment feature 740, for example ahole or hook or hook and loop fastener or the like to permit positioningof lighting element 750. In some embodiments of the present invention,lighting element 750 includes or consists essentially of one or morelight sheets 110. In some embodiments of the present invention, lightingelement 750 includes or consists essentially of a light sheet 110protected by one or more coatings or encapsulations, for example toachieve a water-resistant or waterproof lighting element 750, or toachieve a certain IP rating, for example IP 65, IP66, IP67 or IP68. Insome embodiments, the coating may include one or more of the following:silicone, PDMS, polyurethane, acrylic, or the like. In some embodimentsof the present invention, the coating may be flexible, while in otherembodiments the coating may be substantially rigid. In some embodiments,the coating may be a conformal or substantially conformal coating, whilein other embodiments the coating may not be conformal, for example itmay be molded over one or more portions of light sheet 110, presenting aflat or substantially flat exterior surface. In some embodiments of thepresent invention, a flat exterior surface may be desirable, for exampleto facilitate cleaning.

FIGS. 8A and 8B show another embodiment of the present invention thatincludes a flexible light sheet 110 that may be formed or conformed to acontainer or other object. For example, in some embodiments of thepresent invention, light sheet 110 may be conformed around a waterbottle, a camping stove (identified as 840 in FIGS. 8A and 8B), afishing pole case, tent case, storage case, food case, or the like. Insome embodiments, light sheet 110 may be wrapped around an object like atree or a pole. In some embodiments, light sheet 110 is coated orencapsulated to protect LEEs 140 and substrate 165, as described herein.In some embodiments of the present invention, light sheet 110 includesone or more closure elements to aid in fixing light sheet 110 to theobject. For example, in some embodiments of the present invention, endsof light sheet 110 may be affixed to each other to position light sheet110 by magnets, clamps, hook and loop closures, bungee cords, cableties, rope or string, or the like. In some embodiments of the presentinvention, holder 710, which may include a battery or other powersource, as described herein, may be formed into a shape that fitsadjacent to a portion of the object. For example, in FIGS. 8A and 8B,holder 710 has a shape substantially similar to the bottom of campingstove 840, permitting it to fit compactly into the bottom of campingstove 840. In some embodiments heat generated by LEEs 140 on light sheet110 may be used to further advantage, for example to provide heat to gasin camping stove 840 to ensure a sufficient vapor pressure of gas foroperation of camping stove 840.

FIGS. 8C and 8D show additional embodiments of the present invention,incorporating either a pop-up (FIG. 8C) or roll up (FIG. 8D) light sheet110. The lighting device of FIG. 8C includes a pop-up light sheet 110 ina base 860. In some embodiments of the present invention, base 860 holdsthe power source for light sheet 110 as well as the light sheet 110.During storage, the top 865 is pushed down, moving light sheet 110 intobase 860 where it is protected and resulting in a relatively compactsize for storage. In operation, top 865 is extended, exposing lightsheet 110. In some embodiments of the present invention, light sheet 110is energized when top 865 is extended, while in other embodiments lightsheet 110 may be energized by a separate switch or other means.

In the lighting device of FIG. 8D, the light sheet 110 is rolled up andstored inside holder 870, which may also in some embodiments contain thepower source for light sheet 110. During operation, as shown in FIG. 8D,light sheet is removed from base 870. In some embodiments, duringoperation light sheet 110 may be flat or substantially flat, while inother embodiments light sheet 110 may be curved or otherwise shaped toachieve a specific spatial light distribution pattern.

In some embodiments of the present invention, light sheet 110 typicallyincludes or consists essentially of an array of LEEs 140 electricallycoupled by conductive elements formed on a flexible substrate, forexample, as described in the '807 and '027 applications.

FIG. 9A depicts an exemplary circuit topology, in accordance withembodiments of the present invention, which features conductive elements960, at least two power conductors 910, 920, multiple LEEs 140, andcontrol elements (CEs) 940. In some embodiments, LEEs 140 may beconfigured in a regular periodic array, for example a substantiallysquare or rectangular array, where LEEs 140 are separated by pitch (or“spacing”) 923 in the one direction (for example vertical direction) bypitch 925 in a substantially orthogonal direction. In some embodiments,pitch 925 is the same as or substantially the same as pitch 923. Whilethe geometrical layout and pitches 923 and 925 are described inconnection with the circuit schematic shown in FIG. 9A, such geometry,layout, and pitches are not limitations of the present invention, and inother embodiments the physical layout of the circuit elements may bedifferent than the circuit topology shown in FIG. 9A. Additionally,other embodiments may have different circuit topologies, for exampleLEEs 140 may be electrically coupled in parallel, in a combination ofseries and parallel, or any other arrangement. In some embodiments, morethan one group of electrically connected LEEs 140 may be electricallycoupled to one CE 940, while other embodiments may not require any CEs140. The specific circuit topology is not a limitation of the presentinvention.

The spacing between LEEs 140 shown in the structures of FIGS. 1A, 4, and7 is constant or substantially constant; however, this is not alimitation of the present invention, and in other embodiments thespacing between LEEs 140 may vary. In some embodiments, the light sheet110 may include two or more regions, each having the same orsubstantially the same spacing between LEEs 140, but with differentspacing in different regions. In other embodiments, the spacing betweenvarious pairs or groups of LEEs 140 may be different.

In the examples shown in the figures, substrate 165 is substantiallycovered with an array of LEEs 140; however, in some embodiments, one ormore portions of substrate 165 may not be populated with LEEs 140.

In some embodiments, all LEEs 140 in the lighting system may be drivenat the same or substantially the same current; however, this is not alimitation of the present invention, and in other embodiments differentLEEs 140 or different groups of LEEs 140 may be driven at differentcurrents.

In some embodiments, all LEEs 140 in the lighting system may have thesame optical characteristics, for example luminous or radiant flux, CCT,CRI, R9, spectral power distribution, light distribution pattern,angular color uniformity or the like; however, this is not a limitationof the present invention, and in other embodiments different LEEs 140 ordifferent groups of LEEs 140 may have different optical characteristics.

FIG. 9A shows two power conductors 910 and 920, which may be used toprovide power to strings 950 of LEEs 140. Each string 950 may includetwo or more electrically coupled LEEs 140. LEEs 140 in string 950 may beelectrically coupled in series, as shown in FIG. 9A; however, this isnot a limitation of the present invention, and in other embodimentsother examples of electrical coupling may be utilized, for example LEEsin parallel or in any combination of series and parallel connections.FIG. 9A shows CE 940 connected in series with LEEs 140 of string 950;however, this is not a limitation of the present invention, and in otherembodiments CE 940 may have different electrical coupling between powerconductors 910, 920, or may be absent altogether. For example, in someembodiments CE 940 may be separately electrically coupled to powerconductors 910, 920 and to the LEE string 950, while in otherembodiments each CE 940 may be electrically coupled to two or morestrings. The number of strings electrically coupled to each CE 940 isnot a limitation of the present invention. Combinations of structuresdescribed herein, as well as other electrical connections, all fallwithin the scope of the present invention. Power conductors 910, 920 maybe used to provide power to strings 950, for example AC power, DC power,or power modulated by any other means.

Referring to FIGS. 9B and 9C that depict schematics of exemplary lightsheets 110, a light sheet 110 may feature an array of LEEs 140 eachelectrically coupled between conductive traces 960, and power conductors910 and 920 providing power to conductive traces 960 and CEs 940, all ofwhich are disposed over a substrate 165. As utilized herein, a “wiringboard” refers to a substrate for LEEs with or without additionalelements such as conductive traces or CEs. A wiring board may also bereferred to as a light sheet or a circuit board. FIG. 9B shows a portionof light sheet 110. In the exemplary embodiment depicted in FIG. 9B,power conductors 910, 920 are spaced apart from each other andlight-emitting strings (or simply “strings”) 950 are connected inparallel across power conductors 910, 920. In some embodiments, forexample as shown in FIG. 9B, strings 950 do not cross (i.e., intersect)each other. In other words, power conductors 910, 920 are oriented inone direction and strings 950 are oriented such that they span powerconductors 910, 920 in a different direction. As shown in FIG. 9B,strings 950 are substantially perpendicular to power conductors 910,920. However, this is not a limitation of the present invention, and inother embodiments at least some segments (i.e., portions connecting twoor more LEEs 140), or even the entire strings 950, may define a line(not necessarily a straight line) that is not perpendicular to powerconductors 910, 920 yet is (at least for an entire string 950) notparallel to power conductors 910, 920. In other embodiments strings 950may intersect, for example one string 950 splitting into two or morestrings 950, or two or more strings 950 joining to form a reduced numberof strings 950. In some embodiments conductive elements may cross overeach other without being electrically coupled, and in some embodimentsstrings 950 may cross over or under each other without beingelectrically coupled. In some embodiments all or a portion of one ormore strings 950 may be outside of power conductors 910, 920. Variousexamples of string geometries and conformations utilized in embodimentsof the present invention are described in the '807 and '027applications.

As shown, LEEs 140 are positioned across substrate 165 in a regularperiodic array, although this is not a limitation of the presentinvention, and in other embodiments LEEs 140 may occupy any positions onlight sheet 110. Power conductors 910 and 920 provide power to each LEEstring, for example the string 950 encircled by the dashed line in FIG.9B. Each LEE string 950 typically includes multiple conductive traces960 that interconnect multiple LEEs 140, as well as one or more CEs 940,which in FIG. 9B is in series with LEEs 140. String 950 shown in FIG. 9Bis a folded string, i.e., a string that has three segments electricallycoupled in series but positioned as three adjacent segments. A stringsegment is a portion of a string spanning all or a portion of the regionbetween power conductors 910 and 920 in FIG. 9B. In light sheet 110,some string segments may include LEEs 140 while others do not. However,in other embodiments the distribution and position of LEEs 140 alongconductive elements 960 and string segments may be different. In someembodiments, a string 950 may be a straight string, i.e., a string withno folds, as shown in FIG. 9C. In the example of FIG. 9C, string 950does not include a CE 940. One end of string 950 is electrically coupledto power conductor 910, while the other end of string 950 iselectrically coupled to power conductor 920. As will be discussed, thenumber of segments in a string 950 is not a limitation of the presentinvention. Various examples of straight and folded strings utilized inembodiments of the present invention are detailed in the '807 and '027applications.

FIGS. 9A and 9B illustrate three aspects in accordance with embodimentsof the present invention. The first is the multiple strings 950 that arepowered by the set of power conductors 910, 920. The second is thepositional relationship between the locations of LEEs 140 and CE 940,which is disposed between the conductive traces 960 and between powerconductors 910,920, such that the pitch between LEEs 140 is notdisrupted by the placement or position of CE 940. The third is theinclusion of a CE 940 in each string of series-connected LEEs 140.Combinations of these three aspects enable light sheet 110 to beeconomically manufactured in very long lengths, for example in aroll-to-roll process, and cut to specified lengths, forming lightsheets, while maintaining the ability to tile, or place light sheetsadjacent to each other (e.g., in the length direction), with no orsubstantially no change in pitch between LEEs 140 or in the opticalcharacteristics across the joint between two adjacent light sheets, asdiscussed in more detail in the '807 and '027 applications.

In an exemplary embodiment, CE 940 is configured to maintain a constantor substantially constant current through LEEs 140 of string 950. Forexample, in some embodiments, a constant voltage may be applied to powerconductors 910, 920, which may, under certain circumstances may havesome variation, or the sum of the forward voltages of LEEs 140 indifferent strings may be somewhat different, for example as a result ofmanufacturing tolerances, or the component and/or operational values ofthe element(s) within CE 940 may vary, for example as a result ofmanufacturing tolerances or changes in operating temperature, and CE 940acts to maintain the current through LEEs 140 substantially constant inthe face of these variations. In other words, in some embodiments theinput to the light sheet is a constant voltage that is applied to powerconductors 910, 920, and CEs 940 convert the constant voltage to aconstant or substantially constant current through LEEs 140. The designof CE 940 may be varied to provide different levels of control orvariation of the current through LEEs 140. In some embodiments, CEs 940may control the current through LEEs 140 to be substantially constantwith a variation of less than about ±25%. In some embodiments, CEs 940may control the current through LEEs 140 to be substantially constantwith a variation of less than about ±15%. In some embodiments, CEs 940may control the current through LEEs 140 to be substantially constantwith a variation of less than about ±10%. In some embodiments, CEs 940may control the current through LEEs 140 to be substantially constantwith a variation of less than about ±5%.

In some embodiments, CEs 940 may, in response to a control signal, actto maintain a constant or substantially constant current through LEEs140 until instructed to change to a different constant or substantiallyconstant current, for example by an external control signal. In someembodiments, as detailed herein, all CEs 940 on a sheet may act inconcert, that is maintain or change the current through all associatedLEEs 140; however, this is not a limitation of the present invention,and in other embodiments one or more CEs 940 may be individuallyinstructed and/or energized.

In some embodiments LEEs 140 may include or consist essentially oflight-emitting diodes (LED) or lasers. In some embodiments, lightemitted from light sheet 110 is in the form of an array of bright spots,or light-emission points, resulting in a pixelated pattern. However,this is not a limitation of the present invention, and in otherembodiments light sheet 110 includes different types of light emitters,for example organic LEDs (OLEDs). In some embodiments, light sheet 110may emit light homogeneously or substantially homogeneously, for examplelight sheet 110 may include an array of LEEs 140 behind an optic ordiffuser that spreads the light from LEEs 140 homogeneously orsubstantially homogeneously. In some embodiments, light sheet 110 mayinclude one or more OLEDs emitting homogeneously or substantiallyhomogeneously over light sheet 110.

In the embodiment depicted in FIG. 9B, LEEs 140 are distributedsubstantially uniformly over light sheet 110; however, this is not alimitation of the present invention, and in other embodiments, LEEs 140may have a non-uniform distribution. As will be understood, thedistributions of LEE 140 on light sheet 110 shown in FIG. 9B are notlimitations of the present invention, and other embodiments may haveother distributions of LEEs 140. In some embodiments, one or moreportions of light sheet 110 may be unpopulated with LEEs 140. In someembodiments, the distribution of LEEs 140 on light sheet 110 isspecifically chosen to achieve one or more characteristics, for exampleoptical, electrical, thermal or the like, as described herein. In someembodiments, the distribution of LEEs 140 on light sheet 110 may bechosen to create a certain decorative look.

In some embodiments, light sheet 110 may also be cut to length, asdiscussed in more detail in the '807 and '027 applications. For example,in some embodiments of the present invention light sheet 110 may be cutbetween strings 950.

In some embodiments, light sheet 110 does not require any additionalthermal management or heat-sinking, i.e., the heat generated by LEEs 140is at least partially accommodated by the structure of light sheet 110itself, for example substrate 165 and/or conductive elements 960 and/orpower conductors 910, 920.

As utilized herein, the term “light-emitting element” (LEE) refers toany device that emits electromagnetic radiation within a wavelengthregime of interest, for example, visible, infrared or ultravioletregime, when activated, by applying a potential difference across thedevice or passing a current through the device. Examples oflight-emitting elements include solid-state, organic, polymer,phosphor-coated or high-flux LEDs, laser diodes or other similar devicesas would be readily understood. The emitted radiation of an LEE may bevisible, such as red, blue or green, or invisible, such as infrared orultraviolet. An LEE may produce radiation of a continuous ordiscontinuous spread of wavelengths. An LEE may feature a phosphorescentor fluorescent material, also known as a light-conversion material, forconverting a portion of its emissions from one set of wavelengths toanother. In some embodiments, the light from an LEE includes or consistsessentially of a combination of light directly emitted by the LEE andlight emitted by an adjacent or surrounding light-conversion material.An LEE may include multiple LEEs, each emitting essentially the same ordifferent wavelengths. In some embodiments, a LEE is an LED that mayfeature a reflector over all or a portion of its surface upon whichelectrical contacts are positioned. The reflector may also be formedover all or a portion of the contacts themselves. In some embodiments,the contacts are themselves reflective. Herein “reflective” is definedas having a reflectivity greater than 65% for a wavelength of lightemitted by the LEE on which the contacts are disposed. In someembodiments, an LEE may include or consist essentially of an electronicdevice or circuit or a passive device or circuit. In some embodiments,an LEE includes or consists essentially of multiple devices, for examplean LED and a Zener diode for static-electricity protection. In someembodiments, an LEE may include or consist essentially of a packagedLED, i.e., a bare LED die encased or partially encased in a package. Insome embodiments, the packaged LED may also include a light-conversionmaterial. In some embodiments, the light from the LEE may include orconsist essentially of light emitted only by the light-conversionmaterial, while in other embodiments the light from the LEE may includeor consist essentially of a combination of light emitted from an LED andfrom the light-conversion material. In some embodiments, the light fromthe LEE may include or consist essentially of light emitted only by anLED.

One or more non-LEE devices such as Zener diodes, transient voltagesuppressors (TVSs), varistors, etc., may be placed on each light sheetto protect the LEEs 140 from damage that may be caused by high-voltageevents, such as electrostatic discharge (ESD) or lightning strikes. Inone embodiment, conductive trace segments shown in FIG. 9B or 9C betweenthe LEE strings 950 may be used for placement of a single protectiondevice per light sheet, where the device spans the positive and negativepower traces, for example power conductors 910, 920. These tracesegments also serve to provide a uniform visual pattern of lines in theweb direction, which may be more aesthetically pleasing than a lightsheet with noticeable gaps between LEE strings 950. In a more generalsense, in addition to conductive traces 960 that are part of string 950,additional conductive traces 960 that may or may not be electricallycoupled to other strings 950 and/or power conductors 910, 920 may beformed on substrate 165, for example to provide additional powerconduction pathways or to achieve a decorative or aesthetically pleasinglook to the pattern on the light sheet or to provide a communicationpathway to one or more CEs 940, for example to provide a control signalto the one or more CEs 940. These trace segments also serve to provide auniform visual pattern of lines in the web direction, which may be moreaesthetically pleasing than a light sheet with noticeable gaps betweenLEE strings 950.

In one embodiment, an LEE 140 includes or consists essentially of a baresemiconductor die, while in other embodiments LEE 140 includes orconsists essentially of a packaged LED.

In some embodiments, LEE 140 may include or consist essentially of a“white die” that includes an LED that is integrated with alight-conversion material (e.g., a phosphor) before being attached tothe light sheet, as described in U.S. patent application Ser. No.13/748,864, filed Jan. 24, 2013, or U.S. patent application Ser. No.13/949,543, filed Jul. 24, 2013, the entire disclosure of each of whichis incorporated by reference herein.

In some embodiments, LEEs 140 may emit light in a relatively smallwavelength range, for example having a full width at half maximum in therange of about 20 nm to about 200 nm. In some embodiments, all LEEs 140may emit light of the same or substantially the same wavelength, whilein other embodiments different LEEs 140 may emit light of differentwavelengths. In some embodiments LEEs 140 may emit white light, forexample that is perceived as white light by the eye. In someembodiments, the white light may be visible light with a spectral powerdistribution the chromaticity of which is close to the blackbody locusin the CIE 1931 xy or similar color space. In some embodiments, whitelight has a color temperature in the range of about 2000 K to about10,000 K. The emission wavelength, full width at half maximum (FWHM) ofthe emitted light or radiation or other optical characteristics of LEEs140 may not be all the same and are not a limitation of the presentinvention.

Advantageously, embodiments of the present invention produce light sheet110 having controlled optical characteristics. In some embodiments ofthe present invention, it is advantageous to have multiple light sheets,each of which as a similar CCT (preferably the average CCT of each lightsheet during manufacture or use), having a relatively narrow CCTdistribution. One measure of white color temperature is defined as aMacAdam ellipse. A MacAdam ellipse represents a region of colors on achromaticity chart, for example the CIE chromaticity diagram, and aone-step MacAdam ellipse represents the range of colors around thecenter of the ellipse that are indistinguishable to the average humaneye, from the color at the center of the ellipse. The contour of aone-step MacAdam ellipse therefore represents barely noticeabledifferences of chromaticity.

Multiple-step MacAdam ellipses may be constructed that encompass largerranges of color around the center point. While there are manyrecommendations as to how tight the color temperature uniformity shouldbe (as measured by MacAdam ellipses or other units), a variationencompassed within a smaller step number of MacAdam ellipses (smallerellipse) is more uniform than one encompassed within a larger stepnumber of MacAdam ellipses (larger ellipse). For example, a four-stepMacAdam ellipse encompasses about a 300K color temperature variationalong the black body locus, centered at 3200K, while a two-step MacAdamellipse encompasses about a 150K color temperature variation along theblack body locus, centered at 3200K.

In some embodiments of the present invention, the variation in averageCCT between different light sheets 110 is less than 4 MacAdam ellipses,or less than 3 MacAdam ellipses or less than 2 MacAdam ellipses.

Substrate 165 may include or consist essentially of a semicrystalline oramorphous material, e.g., polyethylene naphthalate (PEN), polyethyleneterephthalate (PET), polycarbonate, polyethersulfone, polyester,polyimide, polyethylene, fiberglass, FR4, metal core printed circuitboard, (MCPCB), and/or paper. Substrate 165 may include multiple layers,for example, a semicrystalline or amorphous material, e.g., PEN, PET,polycarbonate, polyethersulfone, polyester, polyimide, polyethylene,and/or paper formed over a second substrate for example comprising,acrylic, aluminum, steel and the like. Depending upon the desiredapplication for which embodiments of the invention are utilized,substrate 165 may be substantially optically transparent, translucent,or opaque. For example, substrate 165 may exhibit a transmittance or areflectivity greater than 70% for optical wavelengths ranging betweenapproximately 400 nm and approximately 700 nm. In some embodimentssubstrate 165 may exhibit a transmittance or a reflectivity of greaterthan 70% for one or more wavelengths emitted by LEE 140. Substrate 165may also be substantially insulating, and may have an electricalresistivity greater than approximately 100 ohm-cm, greater thanapproximately 1×10⁶ ohm-cm, or even greater than approximately 1×10¹⁰ohm-cm. In some embodiments substrate 165 may have a thickness in therange of about 10 μm to about 500 μm.

Conductive elements, e.g., power conductors 910, 920 and conductivetraces 960, may be formed via conventional deposition, photolithography,and etching processes, plating processes, lamination, lamination andpatterning, evaporation sputtering or the like or may be formed using avariety of different printing processes. For example, power conductors910, 920 and conductive traces 960 may be formed via screen printing,flexographic printing, ink-jet printing, and/or gravure printing. Powerconductors 910, 920 and conductive traces 960 may include or consistessentially of a conductive material (e.g., an ink or a metal, metalfilm or other conductive materials or the like), which may include oneor more elements such as silver, gold, aluminum, chromium, copper,and/or carbon. Power conductors 910, 920 and conductive traces 960 mayhave a thickness in the range of about 50 nm to about 1000 μm. In someembodiments, the thickness of power conductors 910, 920 and conductivetraces 960 may be determined by the current to be carried thereby. Whilethe thickness of one or more of power conductors 910, 920 and conductivetraces 960 may vary, the thickness is generally substantially uniformalong the length of the trace to simplify processing. However, this isnot a limitation of the present invention, and in other embodiments thethickness and/or material of power conductors 910, 920 and conductivetraces 960 may vary. In some embodiments, all or a portion of powerconductors 910, 920 and conductive traces 960 may be covered orencapsulated. In some embodiments, a layer of material, for exampleinsulating material, may be formed over all or a portion of powerconductors 910, 920 and conductive traces 960. Such a material mayinclude, e.g., a sheet of material such as used for substrate 265, aprinted layer, for example using screen, ink jet, stencil or otherprinting means, a laminated layer, or the like. Such a printed layer mayinclude, for example, an ink, a plastic and oxide, or the like. Thecovering material and/or the method by which it is applied is not alimitation of the present invention.

In some embodiments of the present invention, all or a portion ofsubstrate 165 and/or power conductors 910, 920 and/or conductive traces960 may be covered by a layer having pre-determined optical properties.In some embodiments, the optical properties of substrate 165 or acoating material on substrate 165, for example reflectance,transmittance, and/or absorption, may be utilized to further control theoptical characteristics of the lighting system. In some embodiments,substrate 165 or a coating on substrate 165 may be a diffuse reflector,while in other embodiments it may be a specular reflector, and in yetother embodiments it may be designed to have a relatively highabsorbance for light emitted by LEEs 140. In some embodiments of thepresent invention, substrate 165 may have a reflectance of at least 80%or at least 90% or at least 95% to a wavelength of light emitted by LEEs140. In some embodiments of the present invention, substrate 165 may betransparent or substantially transparent to a wavelength of lightemitted by LEEs 140, for example having a transmittance of at least 80%or at least 90% or at least 95% to a wavelength of light emitted by LEEs140. In some embodiments of the present invention, substrate 165 may beabsorbing or substantially absorbing to a wavelength of light emitted byLEEs 140, for example having an absorbance of at least 60% or at least70% or at least 80% to a wavelength of light emitted by LEEs 140. Insome embodiments, substrate 165 or portions of substrate 165 may beconfigured to diffuse a wavelength of light emitted by LEEs 140. In someembodiments, substrate 165 may have two or more regions, where differentregions have different optical characteristics. In some embodiments, thetransmittance of a diffuse region is at least 50%, or at least 70% or atleast 80%, or at least 90% to a wavelength of light emitted by LEEs 140.The remaining portion of substrate 165 in this embodiment has areflecting surface, i.e., a surface reflective to a wavelength of lightemitted by LEEs 140.

In one embodiment, conductive traces 960 are formed with a gap betweenadjacent conductive traces 960, and LEEs 140 and CEs 940 areelectrically coupled to conductive traces 960 using conductive adhesive,e.g., an isotropically conductive adhesive and/or an ACA, as describedin U.S. Pat. No. 8,384,121, filed on Jun. 29, 2011, the entiredisclosure of which is incorporated herein by reference. ACAs may beutilized with or without stud bumps and embodiments of the presentinvention are not limited by the particular mode of operation of theACA. For example, the ACA may utilize a magnetic field rather thanpressure (e.g., the ZTACH ACA available from SunRay Scientific of Mt.Laurel, N.J., for which a magnetic field is applied during curing inorder to align magnetic conductive particles to form electricallyconductive “columns” in the desired conduction direction). Furthermore,various embodiments utilize one or more other electrically conductiveadhesives, e.g., isotropically conductive adhesives, non-conductiveadhesives, in addition to or instead of one or more ACAs. In otherembodiments, LEEs 140 and CEs 940 may be attached to and/or electricallycoupled to conductive traces 960 by other means, for example solder,reflow solder, wave solder, wire bonding, or the like. The method bywhich LEEs 140 and CEs 940 are attached to conductive traces 960 is nota limitation of the present invention.

CE 940 may be one component or multiple active and/or passivecomponents. In one embodiment, power conductors 910, 920 provide a DCvoltage or substantially DC voltage and CE 940 includes or consistsessentially of a resistor, e.g. a current-limiting resistor. The choiceof the resistance value may be a trade-off between a number ofparameters and characteristics that may include, e.g., efficiency andcurrent stability. In general, a larger resistance will result inreduced efficiency but greater current stability, while a smallerresistance will result in increased efficiency but reduced currentstability. Variations in the current may result from variations in theinput voltage (for example across power conductors 910, 920), variationsin forward voltage of the LEEs 140 within the string, variations in thevalue of the current-limiting resistor, variations in current that mayoccur if one or more LEEs 140 in the string become short-circuited orthe like. In the case of CE 940 including or consisting essentially of aresistor, in some embodiments CE 940 is a discrete resistor formedwithin or on conductive traces 960, such as a chip resistor, a bare-dieresistor or surface mount device (SMD) resistor.

As discussed above, in embodiments where CE 940 includes or consistsessentially of a resistor, there may be trade-offs between efficiencyand current stability. While such trade-offs may be acceptable incertain products, other products may require relatively better currentstability at higher efficiencies, and in these cases CE 940 may includeor consist essentially of multiple components or a circuit element, asdiscussed above. In some embodiments CE 940 includes or consistsessentially of a field-effect transistor (FET) and a resistor. Inanother embodiment CE 940 includes or consists essentially of twobipolar junction transistors (BJTs) and two resistors.

In some embodiments, the efficiency and current stability increase withthe number of components, as does the cost. In some embodiments where CE940 includes or consists essentially of multiple components, thecomponents may be in discrete form (i.e., each component individuallyelectrically coupled to conductive traces 960) or in hybrid form (wheremultiple separate components are mounted on a submount, which is thenelectrically coupled to conductive traces 960), or in monolithic form(where multiple components are integrated on a semiconductor chip, forexample a silicon-based or other semiconductor-based integratedcircuit). In some embodiments, CE 940 may be in bare-die form, while inother embodiments CE 940 may be packaged or potted or the like. In someembodiments, CE 940 may include or consist essentially of a bare-dieintegrated circuit. In some embodiments, the integrated circuit includesor consists essentially of multiple active and/or passive devices thatare fabricated on a common semiconductor substrate.

In other embodiments, power conductors 910, 920 may provide AC power, orpower modulated at different frequencies and in these embodiments CEs940 may be selected accordingly or may be omitted. In one embodiment,power conductors 910, 920 may provide a standard line voltage, forexample about 120 VAC or about 940 VAC or about 277 VAC, for example atabout 50 Hz or about 60 Hz. In some embodiments, CEs 940 may accommodatea plurality of input types, and thus be so-called “universal” CEs 940,while in other embodiments different CEs 940 may be required fordifferent input types. The actual component or components of CEs 940 arenot limiting to this invention; however, in preferred embodiments ofthis invention, the positioning of CEs 940 does not disrupt the LEEpitch. In another embodiment of this invention, the positioning of CEs940 is independent of LEE pitch. As discussed herein, CEs 940 and LEEs230 may be electrically coupled to conductive traces 960 using a varietyof means, for example solder, conductive adhesive or anisotropicconductive adhesive (ACA); however, the method of electrical coupling ofCEs 140 and LEEs 230 is not a limitation of the present invention.

In some embodiments, driver 710 is a substantially constant voltagesupply, the output of which is pulse-width modulated to permit dimmingof LEEs 140 on light sheet 110. In some embodiments, driver 710 is a ULclass 2 system having a voltage output not exceeding 60 V.

FIG. 10A shows another embodiment of the present invention. The lightingdevice 1000 of FIG. 10A includes or consists essentially of a lightsheet covered with a protective coating, for example a conformal ornon-conformal coating. FIG. 10B shows one example of substrate 165 andLEEs 140 coated with a non-conformal coating 1020, while FIG. 10C showsan example of substrate 165 and LEEs 140 coated with a conformal orsubstantially conformal coating 1030. In some embodiments, the lightingdevice 1000 may include one or more holes, for example grommeted holes1010, or hook and loop fasteners for ease of mounting; however, this isnot a limitation of the present invention, and in other embodiments the1000 lighting device may be affixed to a structure by other means. Inone embodiment, the lighting device 1000 may be nailed or stapled to asuitable surface, for example a wood or plastic wall of a temporarystructure. FIG. 10A shows an example of a lighting device 1000 extended(e.g., laid flat or substantially flat or having a non-flat (yetunrolled) shape) for operation, while FIG. 10D shows an example of alighting device 1000 rolled up for storage or transportation. In someembodiments of the present invention, lighting device 1000 may includeone or more connectors 1040 (FIG. 10E) for, e.g., electricallyconnecting the lighting device 1000 to another similar or identicallighting device or to a source or external power. In some embodiments,connector 1040 may be a waterproof connector. As shown in FIG. 10E,conductive traces 1050 formed on substrate 165 may interconnect multipleLEEs 140 on substrate 165 as well as provide electrical coupling betweenconnector 1040 and LEEs 140.

In some embodiments, the lighting device of FIG. 10A may be powered byone or more batteries or other power sources, as described herein, whichmay be contained in a separate unit, for example holder 710 (not shownin FIG. 10A). However, this is not a limitation of the presentinvention, and in other embodiments of the present invention the powersource may be incorporated into the lighting device, as shown in FIGS.10F and 10G. In some embodiments of the present invention, one or moresolar cells or photovoltaic devices 1060 may be integrated with lightsheet 110, and these may be used to provide power to light sheet 110, asshown in FIG. 10C. In some embodiments of the present invention, solarcell 1060 may be relatively thin and formed on the side of substrate 165opposite that on which LEEs 140 are formed, as shown in FIG. 10F. Insome embodiments of the present invention, solar cell 1060 may beflexible, while in other embodiments solar cell 1060 may be rigid orsubstantially rigid. In some embodiments of the present invention, thestructure shown in FIG. 10F may be encapsulated or coated to protectsolar cell 1060 and/or light sheet 110.

In some embodiments, a battery, capacitor, or super-capacitor, orcombination of one or more of these, identified in FIG. 10G as 1070, mayalso be incorporated to form a system that incorporates a flexiblebattery having a relatively thin form factor that is formed on the sideof substrate 165 opposite that on which LEEs 140 are formed, as shown inFIG. 10G. In some embodiments of the present invention, battery 1070 maybe flexible, while in other embodiments battery 1070 may be rigid orsubstantially rigid. In some embodiments of the present invention, thestructure shown in FIG. 10G may be encapsulated or coated to protectsolar cell 1060 and/or light sheet 110.

In some embodiments, both a battery and a solar cell may be incorporatedwith a light sheet to form a system that may charge the battery with thesolar cell when light is available, for example during daylight hours,and energize the light sheet when desired from the battery, when littleor no external light is present. A schematic of such a system is shownin FIG. 10H, in which battery 1070 and solar cell 1060 are formed on theside of substrate 165 opposite that on which LEEs 140 are formed. Inpreferred embodiments, both battery 1070 and solar cell 1060 areflexible. In some embodiments of the present invention, the structureshown in FIG. 10H may be encapsulated or coated to protect solar cell1060, battery 1070 and/or light sheet 110.

FIGS. 10F-10H do not show the specifics of how battery 1070 and/or solarcell 1060 and LEEs 140 are electrically coupled. In some embodiments ofthe present invention, elements on the front and back of substrate 165(i.e., on opposite sides of substrate 165) may be electrically coupledthrough electrical vias in substrate 165. FIG. 11A shows an example ofsubstrate 165 with a front conductive trace 960 and a back conductivetrace 1120 electrically coupled through a via 1110. FIG. 10B shows oneembodiment of the present invention illustrating one approach toelectrically couple LEEs 140 to a battery 1070. In this embodiment,power is coupled from battery contact 1130 through via 1110 toconductive trace 960 and LEE 140. Other means may also be used toelectrically couple elements on opposite sides of substrate 165, forexample rivets, staples or the like, as described in the '807 and '027applications.

In some embodiments, light sheet 110 may be incorporated into emergencywarning signs. For example FIG. 12 shows another embodiment of thepresent invention in which a light sheet 110 is incorporated into aportable warning triangle 1200. In some embodiments, warning triangle1200 may fold to a small volume and shape, or may be rolled up to occupya small volume while not in use. In some embodiments of the presentinvention, light sheet 110 may be energized and de-energized to providea blinking indication. In some embodiments of the present invention,light sheet 110 may be cut or formed into one or more shapes, symbols orletters, to provide additional information or indications. For examplelight sheet 110 may be shaped into an arrow, a stop sign, a cross, orother shapes. In some embodiments of the present invention, LEEs 140 onlight sheet 110 may be positioned to form one or more shapes, symbols orletters. FIGS. 12B and 12C show examples of embodiments of the presentinvention incorporating symbols or letters.

FIG. 12B shows a roll-up lighting device, similar to that of FIG. 1A;however, light sheet 110 is configured to include arrow symbols 1210that may be illuminated upon energizing LEEs 140. This lighting deviceincludes a storage compartment, identified here as drum 170, and aflexible illuminated portion, identified as 1215, that may be stored instorage compartment 170. In one embodiment of the present invention,arrow symbols 1210 are formed using shaped light sheet 110, while inother embodiments of the present invention arrow symbols 1210 are formedusing patterns of LEEs 140 on a light sheet 110 that may have a shapenot conforming to that of the symbols 1210. FIG. 12C shows a roll-uplighting device, similar to that of FIG. 10D; however, light sheet 110is configured to include letters 1220 that spell the word “DANGER” thatmay be illuminated upon energizing LEEs 140. In one embodiment of thepresent invention, letters 1220 are formed using shaped light sheet 110,while in other embodiments of the present invention letters 1220 areformed using patterns of LEEs 140 on a light sheet 110 that may have ashape not conforming to that of the letters 1220.

In some embodiments of the present invention, the protective layer, forexample conformal coating 1030 or non-conformal coating 1020, may beshaped to incorporate one or more optical elements to control an opticalcharacteristic of LEE 140. In some embodiments of the present invention,such an optical element may include a refractive or reflecting orFresnel lens, and may be used to control the spatial light distributionpattern of light emitted by one or more LEEs 140, as described in U.S.Patent Application Publication No. 2013/0141909, filed Dec. 4, 2012, theentire disclosure of which is hereby incorporated herein by reference.In some embodiments of the present invention, the protective layer mayinclude or consist essentially of one or more of silicone, PDMS, andpolyurethane, and it may be molded, cast, embossed, or otherwise formedinto one or more flexible optical elements as part of the coating orencapsulation process. FIG. 13 shows one example of an embodiment of thepresent invention having coating 1020 surrounding substrate 165 and LEEs140. As shown, a portion of coating 1020 is formed into multiple opticalelements 1310. In some embodiments of the present invention, each LEE140 is associated with one optical element 1310, while in otherembodiments each optical element 1310 is associated with more than oneLEE 140. In other embodiments, each LEE 140 is associated with more thanone optical element 1310. Manufacture of coating 1020 incorporatingoptical elements 1310 from flexible optically transparent (to awavelength of light emitted by LEEs 140) material results in a flexibleillumination device incorporating optical elements for altering opticalcharacteristics of the light emitted by the LEEs 140. In someembodiments, each optical element 1310 has a height above thesurrounding coating in the range of about 0.5 mm to about 5 mm. In someembodiments, the maximum thickness 1330 is in the range of about 1 mm toabout 7 mm, or in the range of about 1.5 mm to about 5 mm.

In some embodiments of the present invention, the illuminating portionof a portable lighting system, for example the flexible illuminationportion 1215 of FIG. 12B, is bendable or foldable in only one axis;however, this is not a limitation of the present invention, and inpreferred embodiments, the flexible illumination portion is flexible orbendable in more than one direction, for example in two orthogonal orsubstantially orthogonal directions.

In some embodiments of the present invention, the flexible illuminationportion has a radius of curvature, to which it may be deformed withoutdamaging the system, of 50 mm or less, or of 25 mm or less or of 10 mmor less or of 5 mm or less in one direction. In some embodiments of thepresent invention, the flexible illumination portion has said radius ofcurvature in more than one direction, for example in two orthogonal orsubstantially orthogonal directions.

In some embodiments of the present invention, the flexible illuminationportion has a thickness in the range of about 0.5 mm to about 5 mm, orin the range of about 1 mm to about 3 mm.

As described herein, lighting devices of the present invention are basedon a light sheet that includes multiple conductive traces formed on aflexible substrate and that interconnect an array of LEEs. Thecombination of a thin flexible substrate (for example in the range ofabout 12 μm to about 200 μm), thin malleable conductive traces (forexample aluminum or copper having a thickness in the range of about 5 μmto about 100 μm) formed on the flexible substrate and robust electricaland mechanical connections (for example using solder or adhesive)between the conductive traces and the electrical components (LEEs andcurrent control elements and any other desired components) results in anrobust system, both mechanically and electrically, capable of beingflexed, bent and rolled without damage or failure. The small size of thecomponents and the relatively thin substrate and conductive tracescontribute to the ability to achieve relatively small radii of curvaturewithout damage or failure.

In general in the above discussion the arrays of semiconductor dies,light emitting elements, optics, and the like have been shown as squareor rectangular arrays; however this is not a limitation of the presentinvention and in other embodiments these elements may be formed in othertypes of arrays, for example hexagonal, triangular or any arbitraryarray. In some embodiments these elements may be grouped into differenttypes of arrays on a single substrate.

The terms and expressions employed herein are used as terms andexpressions of description and not of limitation, and there is nointention, in the use of such terms and expressions, of excluding anyequivalents of the features shown and described or portions thereof. Inaddition, having described certain embodiments of the invention, it willbe apparent to those of ordinary skill in the art that other embodimentsincorporating the concepts disclosed herein may be used withoutdeparting from the spirit and scope of the invention. Accordingly, thedescribed embodiments are to be considered in all respects as onlyillustrative and not restrictive.

What is claimed is:
 1. An illumination device comprising: a flexiblelight sheet comprising (i) a flexible substrate, (ii) a plurality oflight-emitting elements disposed over the substrate, and (iii) aplurality of conductive traces disposed on the substrate andelectrically interconnecting the plurality of light-emitting elements; astorage unit configured to (i) accept and contain the light sheet in arolled configuration therewithin, the light sheet being wound around anaxis of the storage unit when contained therewithin, and (ii) dispenseat least a portion of the light sheet therefrom via unwinding of thelight sheet from the rolled configuration; a winding mechanism for atleast one of winding or unwinding the light sheet around the axis of thestorage unit; and disposed within or on the storage unit, a power sourcefor supplying power at least to an unrolled portion of the light sheetand thereby illuminating the light-emitting elements of at least theunrolled portion.
 2. The illumination device of claim 1, wherein thewinding mechanism comprises at least one of a hand crank, a motorizedmechanism, or a spring mechanism. 3.-4. (canceled)
 5. The illuminationdevice of claim 1, wherein, when the light sheet is extended from thestorage unit, a thickness of the light sheet is 5 mm or less.
 6. Theillumination device of claim 1, wherein the light sheet comprises anarray of optical elements disposed over the light-emitting elements. 7.The illumination device of claim 1, further comprising a water-resistantor waterproof coating disposed over the light-emitting elements of thelight sheet, the coating substantially conforming to a non-planartopography of the light-emitting elements thereunder.
 8. Theillumination device of claim 1, further comprising a water-resistant orwaterproof coating disposed over the light-emitting elements of thelight sheet, a top surface of the coating being planar notwithstanding anon-planar topography of the light-emitting elements thereunder.
 9. Theillumination device of claim 1, wherein the power source comprises atleast one of a battery disposed within the storage unit, a solar celldisposed on an outer surface of the storage unit, or a connectorconfigured for connection to an external source of power. 10.-11.(canceled)
 12. The illumination device of claim 1, wherein the lightsheet is configured to be wound within the storage unit to a radius ofcurvature of 50 mm or less.
 13. The illumination device of claim 1,wherein the light-emitting elements comprise at least one of bare-dielight-emitting diodes or packaged light-emitting diodes.
 14. (canceled)15. The illumination device of claim 1, wherein the light-emittingelements emit substantially white light.
 16. The illumination device ofclaim 15, wherein a correlated color temperature of the substantiallywhite light is in the range of 2000 K to 10,000 K.
 17. The illuminationdevice of claim 1, further comprising a stiffener disposed along atleast a portion of a leading edge of the light sheet.
 18. Theillumination device of claim 1, further comprising a rotary electricaljoint disposed within the storage unit, the rotary electrical jointbeing configured to preserve electrical contact between the light sheetand the power source during winding and unwinding of the light sheet.19. The illumination device of claim 1, wherein the power sourcecomprises at least one of a flexible battery, a flexible capacitor, or aflexible solar cell disposed on a surface of the light sheet oppositethe light-emitting elements.
 20. The illumination device of claim 1,further comprising, disposed within the storage unit, at least one of(i) drive circuitry configured to convert power from the power sourcefor use by the light-emitting elements, (ii) control circuitryconfigured to control at least one emission characteristic of thelight-emitting elements, or (iii) communication circuitry configured totransmit information to or from the illumination device.
 21. Theillumination device of claim 1, wherein, when the light sheet is fullyextended from the storage unit, a trailing edge of the light sheetremains mechanically anchored within the storage unit.
 22. Theillumination device of claim 1, wherein only the unrolled portion of thelight sheet is illuminated, a rolled portion of the light sheet disposedwithin the storage unit being unilluminated.
 23. (canceled)
 24. Theillumination device of claim 1, further comprising one or more fastenerson the light sheet for positioning of the light sheet when the lightsheet is at least partially extended.
 25. (canceled)
 26. Theillumination device of claim 1, further comprising one or more fastenerson the storage unit for positioning of the light sheet when the lightsheet is at least partially extended.
 27. (canceled)
 28. Theillumination device of claim 1, wherein the plurality of light-emittingelements disposed over the substrate forms a fixed pattern in the shapeof one or more symbols and/or letters. 29.-50. (canceled)
 51. Theillumination device of claim 1, wherein at least one light-emittingelement is coupled to one or more of the conductive traces with ananisotropic conductive adhesive, the anisotropic conductive adhesivebeing activatable via application of at least one of pressure, heat, ora magnetic field.